Mine Fire Recognition and Alarm Method Based on the Number of Corners of Image Contours

Abstract

This invention discloses a mine fire identification and alarm method based on the number of image contour corners. This method uses a camera installed underground to capture and identify images of suspected fires in the monitored area in real time. It also uses the irregular morphology of burning flames to identify and alarm mine fires. This method fully considers the characteristics of fire combustion images, resulting in rapid, accurate, and simple identification, which can buy valuable time for rescue and escape for those in distress underground.

Description

Technical Field

[0001] The present invention relates to a mine fire identification and alarm method based on the number of image contour edges and corners, and the method relates to fields such as digital image processing technology and communication technology. Background Art

[0002] In the coal industry, accidents such as gas, fire, flooding, roof collapse, and coal dust plague coal mine safety. Data shows that among major accidents in my country's coal mines, mine fires and resulting explosions account for the highest proportion and cause the most serious damage. Once a mine fire occurs, if it is not promptly controlled, its spread will rapidly expand, causing significant casualties and property damage. It can also serve as a detonation source, causing explosions in areas of high gas and coal dust concentration underground, causing secondary damage to the underground environment. Therefore, rapid identification of underground fires, timely reporting, and targeted activation of emergency plans and rescue efforts are crucial for safe coal production.

[0003] Existing mine fire monitoring technologies include comprehensive monitoring methods using various sensors, such as temperature, smoke, and gas sensors. Although this type of monitoring has the advantages of high reliability and simple operation, due to the complex underground operation scenes, its layout and maintenance workload is large and it is greatly affected by interference sources; the infrared radiation temperature measurement equipment monitoring method can measure the temperature of the fire source, but the temperature measurement accuracy is greatly affected by underground environmental factors and fire interference sources; the visual feature monitoring method is the current mainstream mine fire monitoring technology, but the existing monitoring technology uses more characteristic variables to determine the fire. Although the information features are rich, they also contain more unstable factors. Comprehensively determining the fire disaster based on multi-lens and multi-frame images will result in a longer determination time and a high missed alarm rate and false alarm rate.

[0004] Therefore, it is necessary to research new methods for rapid mine fire identification to shorten detection time and reduce the false alarm and missed alarm rates of existing monitoring technologies for mine fire perception. Early detection of mine fires and the ability to immediately alert the fire disaster are crucial for timely emergency rescue and saving the lives of those in distress underground. Summary of the Invention

[0005] The purpose of the present invention is to provide a mine fire identification and alarm method based on the number of image contour edges and corners. The method fully considers the characteristics of fire combustion images, can quickly identify fires and fire interference sources, is accurate and simple, and can buy more rescue and escape time for people in distress underground. The fire identification and alarm method includes installing cameras in tunnels, coal mining faces, and excavation faces to monitor the monitoring area in real time, and making a fire alarm judgment based on whether the characteristic relationship between the edges and corners of the outer vertex connected polygons and the inner vertex connected polygons of the suspected fire area on the suspected fire image meets the set conditions, and making a fire judgment in the underground monitoring area based on whether the ratio of the number of fire alarms determined within a set time to the total number of judgments meets the set conditions. When it is determined that a fire has occurred in the underground monitoring area, a fire alarm signal is immediately sent to the monitoring terminal;

[0006] The working process of fire alarm determination includes:

[0007] Step 1: The camera collects images of the monitoring area in real time. After the monitoring image is subjected to image filtering, denoising, image enhancement and image pixel binarization, if the pixel feature value N1 of a single block area on the image is greater than the set threshold H, the image is determined to be a suspected fire image of the single block area; if the pixel feature value N1 of multiple unconnected areas on the image is greater than the set threshold H, the image is determined to be a suspected fire image of the single block area; i When (i≥2) are all greater than the set threshold H, the image is determined to be a suspected fire image of multiple areas, and step 2 is executed; when the suspected fire image determination condition is not met, continuous monitoring is performed;

[0008] Step 2: When there is only a single suspected fire area on the suspected fire image, directly perform contour edge feature processing on the suspected fire area on the suspected fire image, extract the characteristic vertices on the contour, obtain the outer vertex connecting polygon and the inner vertex connecting polygon of the suspected fire area, and calculate the sides, number of angles and side length values of the outer vertex connecting polygon and the sides, number of angles and side length values of the inner vertex connecting polygon; or when there are multiple suspected fire areas on the suspected fire image, perform image segmentation on the multiple suspected fire areas, perform contour edge feature processing on the suspected fire areas in blocks, extract the characteristic vertices on the contour, obtain the outer vertex connecting polygon and the inner vertex connecting polygon of the suspected fire area, and calculate the sides, number of angles and side length values of the outer vertex connecting polygon and the sides, number of angles and side length values of the inner vertex connecting polygon, and execute step 3;

[0009] Step 3: When the edges and corners of the polygons connected to the inner and outer vertices of the suspected fire area outline on the suspected fire image meet the conditions When k ea 、k eb , LB ez are the number of edges, angles and side lengths of the polygon connected to the outer vertex, respectively, k ec 、k ed , LCez are the number of edges, angles, and side lengths of the inner vertices connected to the polygon, respectively. r , z1, z2 are set thresholds; the k r If z1 and z2 are obtained by experimental measurement or artificial setting, then go to step 4, otherwise return to step 1;

[0010] Step 4: Trigger a fire alarm and return to step 1.

[0011] 1. The fire identification and alarm method further includes: the underground monitoring area fire determination process includes a fire alarm determination work that is performed cyclically for a duration of T seconds. When the ratio of the suspected fire image alarm count variable X that meets the fire alarm determination conditions to the total image determination count variable Y is greater than a set threshold S, that is, X / Y>S, it is determined that a fire has occurred in the underground monitoring area.

[0012] 2. The fire identification and alarm method further includes: the outer vertex polygon is a polygon formed by connecting the outer convex vertices of the outline of the suspected fire area on the suspected fire image in sequence by straight lines.

[0013] 3. The fire identification and alarm method further includes: the inner vertex polygon is a polygon formed by connecting the concave vertices of the outline of the suspected fire area on the suspected fire image in sequence by straight lines.

[0014] 4. The fire identification and alarm method further includes: extracting the characteristic vertices on the contour in step 2 as an approximate polygon for the contour of the suspected fire area, obtaining the vertices and coordinates on the contour approximation polygon, and further, judging each vertex on the contour approximation polygon to obtain the convex vertices and coordinates and the concave vertices and coordinates on the contour approximation polygon.

[0015] 5. The fire identification and alarm method further includes: the method for calculating the number of edges of the polygon connected to the outer vertex is: The angle calculation method is The calculation method is the coordinate of the outer convex vertices of each suspected fire area outline; the calculation method of the number of polygon edges connected to the inner vertex is: The angle calculation method is The calculation method are the coordinates of the concave vertices within the outline of each suspected fire area.

[0016] 6. The fire identification and alarm method further includes: the camera includes a visible light camera, a far infrared camera, a near infrared camera and an ultraviolet camera.

[0017] The mine fire identification and alarm method based on the number of image contour corners has the following characteristics:

[0018] 1. The fire identification method of the present invention fully analyzes the contour features of the fire combustion image and the image contour features of the underground fire interference source. The method makes fire judgment based on comprehensive information such as the edges, angles, and side length values of the inner and outer polygons of the suspected fire image contour, which is more conducive to identifying and eliminating the fire interference source and can reduce false alarms and omissions of fire disasters.

[0019] 2. The method of the present invention not only efficiently utilizes the characteristic information of the fire image, but also the algorithm construction of the image processing part is simple and efficient. A single-frame image can quickly determine the fire information. The feature extraction of the method has high recognition and few variables, thereby shortening the judgment time of suspected fires and further buying more escape time for trapped and affected people underground. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the implementation plan of the mine fire recognition and alarm method based on the number of image contour edges and corners.

[0021] Figure 2 Schematic diagram of the fire monitoring and alarm equipment structure.

[0022] Figure 3 Schematic diagram of the fire alarm process of the mine fire recognition and alarm method based on the number of image contour edges and corners

[0023] Figure 4 Schematic diagram of the fire determination process of the mine fire recognition and alarm method based on the number of image contour edges and corners. DETAILED DESCRIPTION

[0024] Figure 1 This is an example of an implementation plan for a mine fire identification and alarm method based on the number of image contour edges and corners. The main components include:

[0025] 1. A storage server (101), wherein the storage server is in communication with an image acquisition camera (105) and is responsible for storing and forwarding real-time video image data of a monitoring area provided by the camera; the storage server is in communication with a fire monitoring alarm device (106) and is responsible for storing and forwarding fire alarm data provided by the fire monitoring alarm device; and provides a monitoring terminal (102) with a service for viewing on-site monitoring data of a monitored area or retrieving historical monitoring image data.

[0026] 2. A monitoring terminal (102), installed above the well, is used to receive the alarm signal from the fire monitoring alarm device (106); it is responsible for providing underground environment monitoring data display services, and the storage server (101) provides real-time, historical data and fire alarm data, and has an audible and visual alarm function; production management personnel can retrieve and query the historical data stored in the storage server (101) through the monitoring terminal.

[0027] 3. Core switch (103), the core management and switching device of the mining Ethernet, is responsible for the management and data exchange of all devices connected to the mining Ethernet, has routing functions, and connects to the Internet.

[0028] 4. Ring network switch (104), underground switching equipment for mine Ethernet, installed underground, multiple ring network switches are connected in a ring network manner.

[0029] 5. Camera (105), image acquisition equipment, installed in underground tunnels, coal mining working faces and excavation working faces, responsible for collecting real-time video images of fire-prone areas such as underground tunnels and working faces; the camera includes a visible light camera, a far infrared camera, a near infrared camera and an ultraviolet camera; the camera has network output and analog video output functions; the network interface is directly connected to the ring network switch (104), and the real-time collected video image data of the monitoring area is transmitted to the storage server (101); the analog video output port is connected to the fire monitoring alarm device (106).

[0030] 6. Fire monitoring and alarm equipment (106), which is responsible for receiving and processing the monitoring video image data collected by the camera (105), has built-in graphic image processing software. When the processed suspected fire image meets the set fire alarm conditions, it sends fire alarm data to the storage server (101); and sends a fire alarm signal to the monitoring terminal (102); it has wired and wireless communication functions.

[0031] 7. Suspected fire area: The camera monitors the suspected fire point area in real time. The image data is monitored and collected and uploaded by the camera in real time.

[0032] Figure 2 This is a schematic diagram of the structure of a fire monitoring and alarm device. The main components of the fire monitoring and alarm device structure include:

[0033] Core processor, graphics processor, storage unit, clock unit, power supply unit, USB interface unit, video image acquisition module, wireless communication unit, network interface unit, SD card interface unit.

[0034] 1. Core processor (201), using Broadcom BCM2837 processor, using ARM Cortex-A53 architecture, 64-bit quad-core 1.2GHz.

[0035] 2. Graphics processor (202), which uses a Dual Core VideoCore IV GPU processor.

[0036] 3. Storage unit (203), using 1GB LPDD2 memory.

[0037] 4. Clock unit (204), using 19.2MHz crystal oscillator.

[0038] 5. The power supply unit (205) uses an AC / DC module with an input of 100V to 240VAC and an output of 12VDC for powering the equipment.

[0039] 6. USB interface unit (206), supporting 4 USB interfaces.

[0040] 7. Video image acquisition module (207), converts the analog video signal into digital video data, inputs the analog video output port connected to the camera (105), transmits the digital video data to the core processor (201) through the USB port, and supports multi-channel video acquisition.

[0041] 8. Communication module (208), responsible for converting the RS485 communication interface to a USB communication interface to connect to other data monitoring devices.

[0042] 9. A wireless communication unit (209), supporting 802.11b / g / n protocols, for wireless communication with monitoring equipment supporting wireless communication.

[0043] 10. Network interface unit (210), responsible for accessing the mining Ethernet and connecting to the ring network switch (104).

[0044] 11. SD card unit (211), used to store system files, library files, monitoring program files, etc., using Linux system management, built-in OpenCV library for video data processing, using a Micro SD card of no less than 4GB.

[0045] An example of a fire alarm process for a mine fire identification and alarm method based on the number of image contour corners is shown below: Figure 3 As shown, the main process includes:

[0046] 1. (301) The internal timer T of the fire monitoring alarm device is set to zero and the timing is started. At the same time, the total number of judgments of images that execute the fire alarm judgment condition is set to 0, and the number of fire alarms of suspected fire images that meet the fire judgment alarm condition is set to 0, and the variable X is executed. Step (302) is executed.

[0047] 2. (302) Further set the total number of judgments of the image executing the fire alarm judgment condition to Y=Y+1. Each time the monitoring image executes the fire alarm judgment condition, the number of judgments variable is accumulated and added by one, and step (303) is executed.

[0048] 3. (303) The fire monitoring alarm device processes the image and performs a fire alarm determination on the suspected fire image. When the set fire alarm determination conditions are met, step (304) is executed, otherwise the process returns to step (302).

[0049] 4. (304) Each time the suspected fire image satisfies the fire alarm determination condition, the fire alarm count variable is incremented by one, i.e. X=X+1, and a fire warning is issued to the monitoring terminal, and step (305) is executed.

[0050] 5. (305) Loop through the fire alarm determination workflow within the set time to determine whether the timer value T is greater than the set time threshold t. When the time value T>t, execute step (306), otherwise return to execute step (302).

[0051] 6. (306) Further determine whether the ratio of the number of fire image alarms X that meet the fire alarm determination condition to the total number of determinations Y of images that execute the fire alarm determination condition is greater than the set threshold value S. When X / Y>S, execute step (307), otherwise return to execute step (301).

[0052] 7. (307) The fire monitoring alarm device sends a fire alarm signal to the storage server (101) and the monitoring terminal (102).

[0053] An example of the fire determination process of the mine fire identification and alarm method based on the number of image contour edges and corners is as follows: Figure 4 As shown, the process includes:

[0054] 1. (401) Cameras are installed in underground tunnels, coal mining faces and excavation faces to collect images of the monitored area in real time and upload them to fire monitoring and alarm equipment for image recognition processing, and further execute step (402).

[0055] 2. (402) The fire monitoring alarm device pre-processes the monitoring image. After the monitoring image undergoes image denoising, image enhancement and image pixel binarization, when there is a single block of pixel brightness characteristic value N1>H on the image, the image is determined to be a suspected fire image of the single block area; when there are multiple unconnected pixel brightness characteristic values on the image , it is determined that the image is a suspected fire image of multiple areas, and step (403) is further executed, otherwise the process returns to step (401).

[0056] 3. (403) The fire monitoring and alarm device performs contour edge feature processing on the suspected fire area on the suspected fire image. When there is only a single suspected fire area on the suspected fire image, the contour edge feature processing is directly performed on the suspected fire area on the suspected fire image. When there are multiple suspected fire areas on the suspected fire image, the multiple suspected fire areas are segmented and contour edge feature processing is performed on each of the suspected fire areas.

[0057] Furthermore, an approximate polygon of the suspected fire area outline on the suspected fire image is made, and the vertices and coordinates of the approximate polygon are obtained. The formula Find the coordinates of the vertices of the approximate polygon, where {(x i-1 ,y i-1 ),(x i ,y i ),(x i+1 ,y i+1 )} is any set of adjacent coordinate points on the approximation polygon. Then determine the coordinate point (x i ,y i ) is to approximate the coordinates of the vertices on the polygon, and traverse the coordinates of all points on the polygon in turn to find the coordinate group of all vertices on the polygon In the formula, e represents the number of blocks in the suspected fire area on the suspected fire image, and step (404) is executed.

[0058] 4. (404) Further determine each vertex on the contour approximation polygon to obtain the convex vertex and coordinates and the concave vertex and coordinates: Based on the coordinates of the approximation polygon vertices obtained in step (403), the total area of the approximation polygon is obtained. Take any vertex coordinate A on the polygon ep (x p ,y p ), then the coordinate points of the two adjacent vertices on the left and right of the coordinate point {A e(p-1) (x p-1 ,y p-1 ),A e(p+1) (x p+1 ,y p+1 )} are directly connected by straight lines to form a new polygon, then the vertex coordinate group of the new polygon is {A e1 (x1,y1)···A e(p-1) (x p-1 ,y p-1 ),A e(p+1) (x p+1 ,y p+1 )···A ej (x j ,y j )}, and further calculate the area of the polygon When SA ep <SA ej When , it is determined that the vertex A ep (x p ,y p ) is the convex vertex in the vertex coordinate group, when SA ep >SA ej When , it is determined that the vertex A ep (x p ,y p ) is a concave vertex in the vertex coordinate group, and step (405) is executed.

[0059] 5.(405) Find the coordinates of all convex vertices Execute step (406).

[0060] 6. (406) Based on the coordinates of the convex vertices, connect them into polygons in sequence and calculate the number of sides of the polygon connected to the vertices. and angle Further find the length of each side Execute step (410).

[0061] 7.(407) Find the coordinates of all concave vertices Execute step (408).

[0062] 8. (408) Based on the coordinates of the inner concave vertices, connect them into polygons in sequence and calculate the number of sides of the inner vertices connected to the polygon. and angle Further find the length of each side Execute step (409).

[0063] 9. (409) When the fire monitoring alarm equipment detects that the characteristic relationship between the number of edges and angles of the polygon connected to the vertex in the outline of the suspected fire area on the suspected fire image meets the condition k ec >k r ,k ed >k r , then execute step (411), otherwise return to execute step (401).

[0064] 10.(410) When the fire monitoring alarm equipment detects that the characteristic relationship between the number of edges and angles of the polygon connected to the outer vertices of the suspected fire area outline on the suspected fire image meets the condition k ea >k r ,k eb >k r , then execute step (411), otherwise return to execute step (401).

[0065] 11.(411) When the fire monitoring alarm equipment detects that the characteristic relationship between the number of edges and angles of the polygons connected to the inner and outer vertices of the suspected fire area outline on the suspected fire image meets the condition k ea ≠k ec ,k eb ≠k ed If yes, then execute step (412), otherwise execute step (401).

[0066] 12.(412) When the fire monitoring alarm equipment detects that the characteristic relationship between the number of edges and angles of the polygons connected to the inner and outer vertices of the suspected fire area outline on the suspected fire image meets the conditions If yes, then execute step (413), otherwise execute step (401).

[0067] 13. (413) Process the fire alarm.

Claims

1. A mine fire identification and alarm method based on the number of image contour edges and corners, characterized by: Cameras are installed in tunnels, coal mining faces, and tunneling faces to monitor the monitoring area in real time. Fire alarms are determined based on whether the characteristic relationship between the edges and angles of the polygons connected to the outer vertices and the inner vertices of the suspected fire area in the suspected fire image meets the set conditions. Fires in the underground monitoring area are determined based on whether the ratio of the number of fire alarms determined within a set time to the total number of determinations meets the set conditions. When a fire is determined to have occurred in the underground monitoring area, a fire alarm signal is immediately sent to the monitoring terminal. The working process of fire alarm determination includes: Step 1: The camera collects images of the monitoring area in real time. After the monitoring image is subjected to image filtering, denoising, image enhancement and image pixel binarization, if the pixel feature value N1 of a single block area on the image is greater than the set threshold H, the image is determined to be a suspected fire image of the single block area; if the pixel feature value N1 of multiple unconnected areas on the image is greater than the set threshold H, the image is determined to be a suspected fire image of the single block area; i When (i≥2) are all greater than the set threshold H, the image is determined to be a suspected fire image of multiple areas, and step 2 is executed; when the suspected fire image determination condition is not met, continuous monitoring is performed; Step 2: When there is only a single suspected fire area on the suspected fire image, directly perform contour edge feature processing on the suspected fire area on the suspected fire image, extract the characteristic vertices on the contour, obtain the outer vertex connecting polygon and the inner vertex connecting polygon of the suspected fire area, and calculate the sides, number of angles and side length values of the outer vertex connecting polygon and the sides, number of angles and side length values of the inner vertex connecting polygon; or when there are multiple suspected fire areas on the suspected fire image, perform image segmentation on the multiple suspected fire areas, perform contour edge feature processing on the suspected fire areas in blocks, extract the characteristic vertices on the contour, obtain the outer vertex connecting polygon and the inner vertex connecting polygon of the suspected fire area, and calculate the sides, number of angles and side length values of the outer vertex connecting polygon and the sides, number of angles and side length values of the inner vertex connecting polygon, and execute step 3; Step 3: When the edges and corners of the polygons connected to the inner and outer vertices of the suspected fire area outline on the suspected fire image meet the conditions When k ea 、k eb , LB ez are the number of edges, angles and side lengths of the polygon connected to the outer vertex, respectively, k ec 、k ed , LC ez are the number of edges, angles, and side lengths of the inner vertices connected to the polygon, respectively. r , z1, z2 are set thresholds; the k r If z1 and z2 are obtained by experimental measurement or artificial setting, then go to step 4, otherwise return to step 1; Step 4: Trigger a fire alarm and return to step 1.

2. The mine fire identification and alarm method based on the number of image contour corners as claimed in claim 1, characterized in that: The underground monitoring area fire determination process includes a fire alarm determination process that is performed cyclically for a duration of T seconds. When the ratio of the suspected fire image alarm count variable X that meets the fire alarm determination conditions to the total image determination count variable Y is greater than a set threshold S, that is, XY>S, it is determined that a fire has occurred in the underground monitoring area.

3. The mine fire identification and alarm method based on the number of image contour edges and corners according to claim 1, characterized in that: The outer vertex connected polygon is a polygon formed by sequentially connecting the outer convex vertices of the outline of the suspected fire area on the suspected fire image with straight lines.

4. The mine fire identification and alarm method based on the number of image contour edges and corners according to claim 1, characterized in that: The inner vertex connected polygon is a polygon formed by sequentially connecting the concave vertices of the outline of the suspected fire area on the suspected fire image with straight lines.

5. The mine fire identification and alarm method based on the number of image contour edges and corners according to claim 1, characterized in that: In step 2, the characteristic vertices on the contour are extracted as an approximation polygon for the contour of the suspected fire area, and the vertices and coordinates on the contour approximation polygon are obtained. Furthermore, each vertex on the contour approximation polygon is judged to obtain the convex vertices and coordinates and the concave vertices and coordinates on the contour approximation polygon.

6. The mine fire identification and alarm method based on the number of image contour edges and corners according to claim 1, characterized in that: The method for calculating the number of edges of the polygon connected to the outer vertex is: The angle calculation method is The calculation method is the coordinate of the outer convex vertices of each suspected fire area outline; the calculation method of the number of polygon edges connected to the inner vertex is: The angle calculation method is The calculation method are the coordinates of the concave vertices within the outline of each suspected fire area.

7. The mine fire identification and alarm method based on the number of image contour edges and corners as claimed in claim 1, characterized in that: The cameras include visible light cameras, far infrared cameras, near infrared cameras and ultraviolet cameras.

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